There are an electrophotography method, a sublime type and melted type heat transcript method, an inkjet method and the like as a method for recording an image that forms an image onto a recording medium such as paper based on the image data signal. The electrophotography method needs a process where an electrostatic latent image is formed on a photoreceptor drum by electrification and exposure, which makes its system complex, and results in the problem of high manufacturing cost, etc. Moreover, for the heat transcript method, its device is cheap, but it has the problem such as high running cost, emitting wastes and the like because an ink ribbon is used. On the other hand, for the inkjet method, its device is cheap, and it can efficiently use ink because ink is exhaled only in needed image part and it forms an image directly onto a recording medium, so that the running cost is low. In addition, it has few noise, and then it is excellent as an image recording method.
As one of the inkjet methods, there is a recording method that uses an ink for use in inkjet printing curable by irradiation of radiant ray.
For example, an ultraviolet-curing type inkjet method draws public attention in recent years in that since the method can be conducted with relative low odor and the method makes it possible to record onto a recording medium which is quick-drying and has no ink absorptivity. The Japanese Un-examined Patent Publication (hereunder referred to as “J.P. KOKAI”) No. 2003-192943 proposes a composition which comprises a polymerizable compound consisting of particular acrylate compounds and a colorant, whose object is providing an ink for use in inkjet printing which can record an image that has no blot, high sensitivity and high adhesion to the recording medium, as well as that is safety with little skin stimulation and sensitization, even onto a substrate that is usually difficult to be recorded directly by the inkjet printing method.
Radical polymerizable acrylate compounds used as a component of ultraviolet-curing type ink are comparatively cheap and are characterized by high polymerization speed, on the other hand, they have defect that the cured inks are easily peeled off from the recording medium (i.e. their adhesion is weak) due to large volume shrinkage.
Epoxy based and oxetane based compounds have been proposed to solve this problem. That is, these compounds have the advantages of the volume shrinkage smaller than that of the radical polymerization and excelling in adhesion because they are cationically polymerizable (see J.P. KOKAI No. 2004-323642). However, they have the faults that their polymerization speed is small and they are expensive at the same time. Thus, it is a current state that there is no polymeric compound that satisfies all the above-mentioned demand performances.